Extraction Teflon

The use of SPME for CE has not (yet) been studied widely. Li and Weber (170) reported an off-line SPME-CE approach for the determination of barbiturates in urine and serum, utilizing a sorbent of plasticized PVC coated around a stainless steel rod. Eor extraction, the coated rod was inserted for 4 min in a Teflon tube containing 50 p.1 of sample, and next the rod was repeatedly desorbed in another Teflon tube which each time contained 5 p.1 of desorption solution. This solution was transferred to an injection vial and an aliquot was injected into the CE system (Eigure 11.19). The extraction procedure appeared to be selective and effectively allowed the handling of very small samples. 

Acetone powder (1.5 g) was extracted 4 times with 0.1 M sodium borate buffer (pH 7.6) at 4°C, homogenizing each time with a glass grinder equipped with a Teflon pestle. The first extraction was carried out with 80 ml of the buffer, followed by 3 times with 70 ml each of the buffer. Each homogenate was centrifuged at 16,000 g for 5 min. All supernatants were combined. 

To a mixture of 1,3-dibromobenzene (4.36 g, 18.49 mmol), 1,3-phenylene diamine 111 (2.00 g, 18.49 mmol), NaO-t-Bu (3.73 g, 38.84 mmol), Pd2(dba)3 (0.339 g, 0.37 mmol), and BINAP (0.691 g, 1.11 mmol) in a heavy-walled flask equipped with a Teflon valve was added THF (15 mL) under inert atmosphere. The flask was sealed and heated to 90°C. After 24 h, die reaction mixture was cooled to room temperature and neutralized using 0.2 mol equivalents of 2.4 N HC1 in MeOH. The polymer was precipitated from hexanes, filtered, and dried under vacuum. The dried polymer was redissolved in THF, filtered through Celite, and reprecipitated. The solid was collected by filtration and dien purified by Soxlilet extraction with CH2C12 overnight. After drying under vacuum, a green-tan solid was obtain in 106% yield. GPC (NMP, polystyrene standards) Mw = 39,000 ... 

B. 4-Nonylbenzoic acid. A 500-mL, round-bottomed flask equipped with a Teflon-coated magnetic stirbar and a reflux condenser is charged with 4-nonylbenzoic acid methyl ester (10.07 g, 38.37 mmol), 100 mL of methanol (Note 1), and 96 mL of 1M aqueous NaOH. The resulting mixture is heated at reflux for 18 hr and then allowed to cool to room temperature. The reaction mixture is carefully acidified by addition of 200 mL of 1M aqueous HC1, and the resulting solution is transferred to a separatory funnel and extracted with four 250-mL portions of ethyl acetate. The combined organic layers are dried over Na2S04, filtered, and concentrated by rotary evaporation at reduced pressure. The residue (ca. 9.5 g) is recrystallized from 70 mL of hexanes to give 8.32-8.35 g (87-88%) of 4-nonylbenzoic acid as a white solid (Notes 6, 7). 

Pectins were extracted from isolated cell walls of 5-week-old wheat plants using different methods. Enzymic digestions of the cell walls involved pectinases such as a commercial pectolayse or recombinant endopolygalacturonase [Maness Mort, 1989]. Chemical extractions involved the chelating agent imidazole [Mort et al., 1991] or solvolysis with anhydrous HF at 0 °C in a closed teflon line [Mort et al., 1989] followed by imidazole extraction. 

Extraction of sec-butanol from isobutene Polymerization to form Teflon... 

Residual pendimethalin in various crops was determined as follows." A 10-20-g amount of fruits or vegetables was extracted by blending twice with 200 mL of methanol. Grasses and mint were extracted with 200 mL of methanol-water (1 1, v/v). Nuts were extracted with 200 mL of n-hexane-2-propanol (3 1, v/v). For the residue analysis of the dinitroaniline herbicides butralin, dinitramine, ethalfluralin, pendimethalin, and trifluralin, a tomato sample (5 g) was extracted twice with 20 mL of methanol in a Sorvall homogenizer and filtered through filter paper. Benfluralin and trifluralin residues in the sample (10 g) were extracted with 100 mL of acetonitrile-water (99 1, v/v) in 250-mL screw-cap jars with Teflon liners rotated for 1 h on an end-over-end shaker (40 rpm). ... 

Concentrate the acetonitrile extracts obtained above to dryness below 40 °C with the rotary evaporator. Dissolve the residues in 2 mL of acetone. Quantitatively transfer the acetone extracts to a culture tube with a Teflon screw-cap containing 250 xL of acetone-olive oil keeper (1 1, v/v). Evaporate the acetone on a heating block not exceeding 40 °C under a stream of air. Wrap the threads on the Teflon culture mbe with Teflon tape and add 2.0 mL of 50% (w/w) sodium hydroxide. Cap tightly and heat the Teflon culture tube at approximately 200 °C for 3 h. 

Quantitatively transfer the hydrolysis reaction solution to a 50-mL glass culture tube with a screw-cap by rinsing witli 3x5 mL of deionized water followed by 5 mL of 30% (v/v) sulfuric acid and one additional 5 mL of deionized water. Rinse the Teflon culture tube with acetone and transfer to the glass culture tube. Extract the acidic aqueous phase (pH 1) with 3 x 2.5 mL of toluene. Pass each upper toluene phase through approximately 3 g of anhydrous sodium sulfate contained in a 6-mL disposable filtration cartridge into a 10-mL volumetric flask. Adjust the volume of the solution to 10 mL with toluene. Condition a 3-mL diolsilane bonded silica gel SPE cartridge with two column volumes of toluene. Load a 5-mL aliquot of toluene solution and collect the eluate in a 125-mL round-bottom flask. Elute the column with an additional 50 mL of toluene (use the 75-mL reservoirs) and collect the eluate in the same round-bottom flask. Concentrate the toluene extract to approximately 3.0 mL at 40 °C under weak reduced pressure with a rotary evaporator. 

A significant advance was made in this field by Watarai and Freiser [58], who developed a high-speed automatic system for solvent extraction kinetic studies. The extraction vessel was a 200 mL Morton flask fitted with a high speed stirrer (0-20,000 rpm) and a teflon phase separator. The mass transport rates generated with this approach were considered to be sufficiently high to effectively outrun the kinetics of the chemical processes of interest. With the aid of the separator, the bulk organic phase was cleanly separated from a fine dispersion of the two phases in the flask, circulated through a spectrophotometric flow cell, and returned to the reaction vessel. 

Observation of effects. Seven to 14 days after exposure to test compounds, length, number of leaves and presence of stomata in sprouted winterbuds were determined. FOr sago pondweed tubers, length, number of new daughter plants and presence of roots were determined. Hydrilla explants were evaluated for number of and length of new shoots. In some experiments the chlorophyll-a content of the apical 2 cm on apical explants was determined by 3 successive extractions in 90% acetone using a power-driven Teflon pestle. Absorbance of Millipore-filtered (.45p ) acetone extracts was determined at 6 30, 6 45, 6 6 5 nm on a spectrophotometer. Chlorophyll-a was calculated by equations of Strickland and Parsons (8). 

Principles and Characteristics In the Parr bomb extraction technique (see also Section 8.2.1.2), a Teflon-tetrafluoroethylene fluorocarbon resin lined vessel is used for sample containment. A sample (typically 1 g) is heated in a small volume of solvent at T, t, p of choice. 

A PET oligomer isolation method has utilised chloroform extraction in a Parr bomb lined with a Teflon-TFE fluoro-carbon resin [40]. The analytics of fluoropolymer processing aids (combustion analysis, XRF, EUR, 19F NMR, OM) have recently been described [29]. Combustion analysis (Parr Oxygen Bomb Calorimeter) can be used for quantitative analysis... 

Air samples can be analyzed by passing a known volume of air through a Teflon filter to catch air particulates followed by an activated charcoal filter to trap any gas-phase materials. The Teflon filters are extracted with hexane, concentrated, and analyzed by GC/MS. The charcoal traps are desorbed with carbon disulfide, concentrated, and analyzed by GC/MS. No performance data were reported (Dannecker et al. 1990). 

Air (particulates and gas) Sequential collection on Teflon filters and charcoal tubes solvent extraction with hexane (filters) and carbon disulfide (charcoal tubes) GC/MS Not specified Not specified Dannecker et al. 1990... 

After the Teflon stopcock is closed, the reaction vessel is transferred to a water bath maintained at 60°. The lower end of the vessel should be immersed to within about 1 in. below the fritted-glass retainer. As refluxing of the bromine proceeds, a liquid layer should accumulate above the fritted-glass retainer. If this does not happen, some bromine should be poured through the bypass arm so that a liquid layer ca. 1 in. thick is maintained on the frit. It is essential that liquid bromine contact the tribromide in order to attain efficient conversion to tetrabromide. As the reaction proceeds, the product, dissolved in liquid bromine, extracts into the lower vessel and deposits there as fine black crystals. 

---